A classic relay knows two states. A digital output knows any number – and this is precisely what creates the functions that could otherwise only be built with additional electronics: dimming, flashing, time control, and rule-based processes.
Dimming: when it works and when it doesn't
Dimming is not achieved by lowering the voltage, but by switching the output on and off very quickly. The ratio of on-time to off-time determines the brightness. For LED lighting, this is the appropriate method because the full voltage is maintained and only the time varies.
Not every consumer can handle this. Roughly speaking:
- Suitable: LED lighting, provided the bulb or its ballast is approved for this type of control.
- Conditionally suitable: Fans and small motors – they run, but can become audible.
- Not suitable: Electronics with their own power supply, compressors, anything with inrush current.
The question of whether a light source is dimmable is decided by its data sheet, not the switching module. A non-approved light source flickers, hums, or simply has a shorter lifespan.
NoteDimmable circuits belong in the planning stage, not in later configuration. Which channels are to be dimmed also influences the selection of light sources – and these are purchased before installation.
Flashing and Timers
Flashing is the simplest time-controlled function and the reason why a separate flashing relay is installed in classic systems. With a digital output, this component is no longer necessary.
Timer control is the more practically useful case. Two patterns are common:
- Run-on. A consumer continues to run for a defined period after being switched off – typical for fans.
- Automatic shutdown. A consumer switches itself off after a set period. This is the most effective protection against a circuit that someone switches on and forgets.
Both patterns replace something that would otherwise require discipline – and discipline is the most unreliable component in any on-board electrical system.
Rule-based processes
Beyond individual functions, logic rules can be stored: conditions under which an output switches without anyone pressing a button.
Two functions are prepared for this and cover the most common requests. The master light function switches several lighting circuits with one command – the circuit that is activated when leaving. Conversely, the panic function switches on everything that produces light with a single press.
When designing your own rules, restraint is advisable. A rule that cannot be explained in six months will be a problem in the event of a fault, not a help. What happens automatically belongs in the same assignment table as the channel assignment.
Control via different signal types
Outputs can be controlled via classic switches, digital signals, or analog input signals, freely configurable and automatically synchronized.
Synchronization is the point that makes the difference in everyday life: If a circuit is switched on via the display, the corresponding button shows the same status – and vice versa. With a classic toggle switch, this exact problem arises as soon as a second control point is added.
In what order to configure
- Basic function per channel: On/off, dimming, or motor control.
- Current limitation according to the installed cross-section.
- Time functions where they serve a specific purpose.
- Battery protection staggered according to consumer priority.
- Logic rules last – and only those that can be justified.
Typical errors
- Non-dimmable light sources dimmed. Manifests as flickering or humming and shortens lifespan.
- Dimming planned only after installation. The light sources are then already purchased.
- Too many logic rules. Every automation that no one can explain anymore becomes its own problem in the event of a fault.
- Timer instead of troubleshooting. An automatic shutdown does not replace a defective consumer.
- Automations not documented. What switches by itself must be written down – otherwise the next person will look for a fault that doesn't exist.
